The present invention relates to a boiling/cooling apparatus of a large number of high heat generation members being arranged in high density inside a limited space such as integrated circuits for electronic computers, that is, to a semiconductor cooling apparatus.
In a conventional semiconductor cooling apparatus such as one disclosed in U.S. Pat. No. 3,741,292, a substrate on which chips are mounted is dipped within a refrigerant liquid enclosed into a container, boiling bubbles generated from the chips ascend and reach a steam reservoir at the upper portion and the steam is condensed by a cooling plate projecting into the container and is then returned to a liquid reservoir at the lower portion.
According to this method, however, the contact between the chips fitted to the upper portion and the refrigerant liquid drops due to the boiling bubbles that are built up from the below portion. Therefore, it has been necessary to increase the size of the container so that a greater amount of the refrigerant liquid can be supplied to the upper portion and the boiling bubbles can be scattered.
Another prior art example is described in Japanese Patent Laid-Open No. 204156/1982. In this prior art apparatus, a heat generation member is dipped into a refrigerant liquid, the boiling steam is condensed and liquefied by a condenser disposed at the upper portion of the container and guide plates disposed between the heat generation member and the condenser permit the circulation of the boiling steam and the condensate liquid without mutual interference.
However, this method involves the problem in that when the exothermic quantity of the heat generation member is great, the heat generation portion becomes an ascending gas-liquid current as a whole due to vigorous boiling at the heat generation portion and the liquid that has been condensed and drops cannot be supplied sufficiently to the heat generation member. Accordingly, the cooling performance in this prior art apparatus drops.
The above stated prior art examples do not consider the method of bringing the entire heat generation portion into contact with the refrigerant liquid and invite the drop of cooling performance. Even if they consider such a method, the container becomes greater in size in order to secure sufficient contact In a cooling structure wherein a large number of substrates on which high exothermic chips such as chips for computers are mounted and laminated, the wiring distance between the substrates gets elongated and a higher calculation speed cannot be accomplished smoothly.
Further, another prior art example is described in Japanese Patent Laid-Open No. 85448/1987. In this prior art apparatus, an apparatus in which a plurality of LSI's are mounted on a vertically disposed substrate is dipped into the refrigerant liquid, LSI apparatus is boiling-cooled, due to the insertion of the heat exchanger pipe into the refrigerant liquid, thereby the cooling performance is improved.
In the former above stated prior art example, when non-condensable gas leaks into the refrigerant liquid, the cooling performance is lowered remarkably, besides in this Japanese Patent Laid-Open No. 85448/1987, since the heat exchanger pipe is inserted into the refrigerant liquid, even though the non-condensable gas leaks into the refrigerant liquid container, it is possible to maintain the cooling performance at a predetermined value.
However, the cooling performance value itself is lower than that of the above stated prior art example in which the heat exchanger pipe is inserted into the refrigerant steam being, the refrigerant steam generated by boiling at LSI portion is concentrated at the heat exchanger pipe portion, thereby the cooling performance is improved.
However, in recent years the exothermic quantity per unit LSI chip has increased and further the interval between adjacent LSI chips tends to narrower comparatively, accordingly the steam amount per unit volume has increased.
At the apparatus in which the heat exchanger pipe is inserted into the refrigerant liquid, the refrigerant steam is concentrated at the heat exchanger pipe portion. However, in the high integration semiconductor elements the steam amount increases, then the refrigerant steam is accumulated and this refrigerant steam covers around the LSI chips, therefore there is problem that the boiling performance of the LSI chip becomes lower.